We are currently testing the preview release of Windows 2012 R2 for the following:
1. agent compatibility
7. app server support
Development has found some issues with provisioning and are working with Microsoft to resolve the issues. The goal is to have 2012 R2 supported with the BSA 8.5 release which is tentatively planned for Q1 2014.
Microsoft will release 2012 R2 on Oct. 18th. Our support policy of BSA is to support new Operating Systems within a 6 month window after release so we are on target with 8.5.
Akbar, thank you so much for your response.